Layers of volcanic ash on the eroding edges of the icecap of an Icelandic volcano. Does it remind you of something by any chance?

Well…? It made me think of van Gogh’s Starry Night. The oil rendering is too bright a contrast but the reed pen version is pale.

The drawing Cypresses in Starry Night, by van Gogh after the painting in 1889 (Source: Wikipedia)

And here’s another one

The Swedish Baltic Sea island of Gotland came first in a survey to elect the best picture taken from US space agency NASA’s Landsat program, which celebrated its 40th anniversary this week. From The Local.se Click for link.

Heavier ash – different erosion pattern…

And altogether different again…

This could be a black and white image of the wood grain in a carving, but isn’t –

Speaking of which: the display of banding in the reentrants of the polar caps demonstrate the prior movement of the glaciers of Mars, but the thickness evidence or “facts” given show that the glaciers must be currently flowing: water ice will flow after about 100m on earth, or 300m on Mars (gravity about 0.35 Earth). I haven’t been able to figure out what the basal temperature on Mars would be, but it has to be higher than the average surface temperature of about -60C (otherwise there would be a net heat flow INTO Mars from the sun, not a balance as measured). So a flow restriction due to cold may be real, but if it were 50% greater, then the minimum thickness for water-ice to flow on Mars might be 450m. If, instead of water-ice, much of the caps of Mars were CO2, with a density greater than water-ice, as solid CO2 sinks in water, then we’re in the 400m thickness perhaps for the ice caps of Mars to be flowing.

The ice caps are estimated to be, in places 3000m thick. More than enough.

Prior glacial periods had the ice caps further north and south. There are large, sinuous eskers outside the current limit of the southern ice cap, some multi-hundred kilometers long. These are obvious on the images available from Google Mars. These eskers also demonstrate that inside the icecap temperatures are much higher and were much higher in previous times. Along the limit of the norther ice caps you can see a flat, wide lake or sea bottom with multiple, large “boils” that have internal, round, depressed water features (dark on radar): these would be breached pingos, similar to what you find on the Arctic coast. The pingos are neither on the edges nor in the center of the lake/sea bottom, which I interpret as meaning that you require a certain thickness of sediment to trap the underlying water, but not too much sediment to prevent the greater bouyancy of water-ice from pushing through the cap rock.

Doug,
Thank you – that’s fascinating and definitely something I would like to explore further. I didn’t know Google Mars existed. What you’ve written about is the basis of a good post – I don’t suppose you’d consider a guest post? If not I’ll hope to get to it eventually myself.